Pavement.



PATBNTED MAR. 13, 1906.

. i.' s; Q f,

J. I. MGDONALD. PAVEMENT. APPLIOATIDN 'FILED JAN. 30.1905.

Witnesses ua Mm 22... fywf JOHN I. MCDONALD, OF ST. JOSEPH,

Parleur OFFICE- MISSOURI.

PAVEMENT.

Application led January 30,

To fir/ZZ whom it may concern:

Be it known that I, JOHN IQMcDoNA'LD, a citizen of the United States, residing at St. Joseph, in the county of Buchanan and State of Missouri, have invented new and useful Improvements in Pavements, of which the following is a specification.

My invention relates to paving, its object being to enable the construction in arelatively cheap and simple manner of a broken-stone or macadam roadwayr of high efficiency and great durability. It is we l known by engineers that the efliciency of such roadway depends very largel T upon the character of the filler employed to close the voids between the fragments of stone, the effectiveness of such filler-.or binder inmaintaining the compactness and solidity of the roadway varying with the cementitious or holding properties of the material used. Clay, sand, or stone-screenings are ordinarily employed for this purpose, ut are subject to the defects that they are dissolved to greater or less extent by water, are easily eroded by heavy rains, and, on the other hand, lose what little binding power they possess in periods of continued drouth, allowing the roadwa r to Hravel or become loose and rough, and the same is built upon serious damage .by tion, roadways so constructed are exceedlngly dusty in dry weather and muddy in wet and are difiicult to clean under all conditions f b without detriment to the surface.

substances and in late years of various compositions in which refined asphalt is the-important ingredient. All such compositions have to be heated to the iuid state and poured upon the stone fragments already spread in statu or first mixed therewith by mechanical means. manifestly demands a plant for the preparation of the composition, expertness in the procedure, and much expense in material employed.

My invention contemplates4 the use of a natural bituminousstone in a ground state for such binder. The stone, which is found either as sandstone or limestone in many Specification of Letters Patent.

Patented March 13, 1906. 1905. serial No. 243,296.

sil t into the voids and 1s then spread in proper proportion upon Ythe layer of stone or gravel 'in situ and the Whole rolled, as usual in laying macadam. The presence of the bitumen or asphalt not only gives such natural filler enormously-increased holding` power u )on the fragments, but under rolling and subsequent tr`aflic the filler becomes as hard and compact as the stone, making a roadway free om dust, waterproof, easily cleaned and washed, and highly durable. Its durability is further enhanced by the fact that under traflic, and thus maintain the smoothness` and integrity of the roadway.

n practice itis not essential that the whole bod of the pavement scriiied. The lower stratum acting as a. base may be constructed with the use of any convenient filler and the wearing-surface preferably three or fourv inches deep, as above. l t. is advisable also in laying the wearing-surface to put it down in relatively thin successive layers, so that the natural-stone filler may ave every opportunity to thoroughly lill the voidsto repletion before the final rolling.

The accompanying drawing represents a. vertical section of a piece of ,pavement elnodying my invention.

n a concrete base 1 is built up the mixture of broken stone 2 and bituminous filler 3, as

above set forth, the up er layers being preferably composed of sma ler fragments ol' stone than the lower ones.

What I claim is,`

l. A pavement composed of hard broken stone anda binder of ground natural bituminous stone mixed and rolled without heating'.

2. A pavement having its upper portion composed of hard broken stone mixed with a binder of finely-ground natural bituminousl stone.

3. A pavement having a foundation of maeadam, and a top portion of hard broken stone. the voids being filled with a binder ol' ground natural bituminmis stone. i

be vlaid as above de- 4. The process of making si pavement which consists in grindingnatuml bituminous stone,

mixing it with hard broken stone. to consti'- tute a. binder therefor, spreatiing the mixture S on -a suitable foundation, and subjecting the Whole to heavy. pressure In testimony Whereo have, signed my i JOHN I. MGDONALD.

Witnesses:

JOHN S. EDWARDS, G. A. TRENHOLM. 

